1. Field of the Invention
The present invention relates to the construction of fiberboard boxes and more particularly the invention relates to a new joint construction for the manufacture of fiberboard boxes. The fiberboard may be the most commonly used of corrugated fiberboard or a solid fiberboard having sufficient thickness and strength characteristics to satisfy the strength values required for a container.
2. Description of the Prior Art
Fiberboard boxes or containers and more particularly corrugated fiberboard boxes or containers have been constructed in a wide variety of configurations and forms. A very common type of construction consists of a flat box panel which includes a plurality of side panels and corresponding end panels or flaps and a tab extending from one of the end panels which is adapted to be joined to the corresponding side panel when the flat blank is folded into a box configuration. The joint tab is joined to the side panel by what is known in the trade as a "manufacturer's joint". In the employment of this joint, the two ends of the finished box blank are brought together and permanently fastened with glue tape, or adhesive, or wire staples. The tab which forms the joint may be an extension of either the end panel which is fastened to a side panel, or it may be an extension of the side panel which is fastened to an end panel. The tab may also be fastened either inside or outside of the adjoining panel.
The manufacturer's joint, when made with wire staples, is commonly referred to as a "stitched joint". Each of these prior art constructions has certain inherent disadvantages. When a stitched joint is employed, the wire staples project slightly into the box from the inner surface of the fiberboard to an extent where the staples may scratch, mar or otherwise injure objects contained in the box, unless the staples are coated, covered or otherwise protected. Such protective coating and its inclusion in the box construction obviously increases the cost of fiberboard box manufacture. Such stitched joints, however, are strong and have maximum strength as compared with other types of joints. Stitched joints also have a further disadvantage in that the staples are normally manufactured from steel and, therefore, are subject to rusting which, under adverse conditions, could damage the contents of the container.
Taped joints, which are not lap joints, do not include a tab, have been commonly used in fiberboard box construction. In such constructions the edge of a side panel is butted to the edge of an end panel, and a length of glue tape is applied to the butted edges throughout the joint's length. Not only does a tape joint require tape having a special glue, but the joint is normally weaker and is further subject to joint deterioration in the presence of moisture.
The third type of joint referred to, a glued joint, is constructed by gluing the tab projecting from one of the box panels to the adjacent panel.
Although glued joints are cheaper to manufacture than stapled or taped joints, a glued joint can come apart because of the insufficient application of glue, or because of the use of the wrong type of glue, and more particularly such joints can be severely weakened in the presence of an excess amount of moisture. Numerous other types of joints have been proposed in the manufacture of fiberboard boxes, and many of those are discussed in my earlier filed application, Ser. No. 570,033, filed Jan. 11, 1984, entitled BOX CONSTRUCTION, now abandoned.
None of the prior art patents, of which I am aware, suggest a way in which a manufacturer's joint can be constructed in a manner which will lend the box strength, with characteristics similar to those resulting in a stapled box construction, but which does not employ staples, and which is lower in cost to manufacture than either glued or taped constructions, and which is substantially stronger than the glued or taped constructions. Accordingly, a need has existed for a maximum strength, minimum cost, corrugated fiberboard box construction which may be manufactured by typical cutting, folding and box forming procedures, and which includes a lapped joint that eliminates the defects which have characterized the prior art.